The use of hose clamps for compressing and sealing fluid-carrying hose connections is well known in the art. Such clamps are commonly utilized on flexible hoses in automotive vehicles and in pneumatic and hydraulic devices where hoses are used to carry fluid under pressure or vacuum.
There are several types of screw-type hose clamps in common use. They may be broadly characterized as (1) a band or strip clamp, with tangential screw take-up means (2) a band or strip clamp, with radial screw take-up means, and (3) a wire clamp, with tangential screw take-up means, such as disclosed in Tetzlaff et al, U.S. Pat. No. 3,454,996 granted July 15, 1969. Disclosures of representative tangential and radial band clamps can be found in Tetzlaff et al, U.S. Pat. Nos. 3,407,448 and 3,407,449, both granted Oct. 29, 1968.
A band clamp is a unitary strip of metal or the like, formed in a single loop, and provided with slots or recesses or indentations or the like by means of which the ends of the loop can be drawn towards each other to diminish or reduce the circumference of the loop to compress and seal the flexible hose which it circumscribes. A screw thread is utilized to cooperate with the formations provided on the band to cause the tightening action on the loop.
In its simplest form, a band clamp can be provided with upstanding ears on its ends, which are spaced from each other, and a screw or a bolt and nut traverse the ears to draw them toward each other. However, in this simplified form, there is no overlap of the ends of the band, so the hose is not completely circumscribed and sealed by the clamp. For that reason, the more sophisticated overlap forms of band clamps are more effective and are preferred where complete circumferential sealing is desired.
Similarly, a wire-form clamp can be provided with opposed ears which are traversed by a tightening screw arrangement disposed tangentially to the clamping loops. In more sophisticated form, complete seal can be approached by utilizing an underlying bridging or saddle member to create the effect of overlap and thus embrace the hose in the open area between the opposed ears.
It is commonly accepted and acknowledged in the art that the wire clamp is both a more effective and a less costly hose clamp than the band clamp. The band clamp distributes the hose-compressing force over a broad surface contact area. In contrast, the axially-spaced pair of loops in a wire clamp concentrate the compressing force in the much smaller area established by the diameter of the cylindrical wire elements, thus establishing a more effective seal at each of two axially-spaced areas on the hose. Furthermore, by reason of such axial spacing, the wire clamp could, if desired, be positioned to clamp and seal a hose both in front of and behind the circumferential retaining bead customarily provided on the fixed conduit to which the hose is connected. This function cannot be achieved by the single loop of a band clamp.
For the foregoing reasons, the tangentially-adjusted wire clamp has long been favored over the tangential band clamp in most applications. However, with the increasing emphasis on high productivity and the use of automation and power tools on assembly lines, the tangentially-adjustable clamp created a problem by tending to rotate away from the tightening tool when tangential force was applied to the adjusting screw. The structure of the band clamp had the stability to lend itself to design modification for purposes of mounting the adjusting screw in a radial, rather than a tangential, posture. The radial posture of the screw eliminated the problem of tool-induced rotation of the clamp around the hose during the assembly process. The wire clamp structure could not be successfully adapted to accept a radial adjusting screw, so the clamping and cost advantages of the tangential wire clamp were reluctantly sacrificed to the speed and convenience of the radial band clamp, which eliminated the aforesaid rotation problem.